Exogenous application of allelopathic water extracts helps improving tolerance against terminal heat and drought stresses in bread wheat (Triticum aestivum L. Em. Thell.)

Abstract

The allelopathic water extracts (AWEs) may help improve the tolerance of crop plants against abiotic stresses owing to the presence of the secondary metabolites (i.e., allelochemicals). We conducted four independent experiments to evaluate the influence of exogenous application of AWEs (applied through seed priming or foliage spray) in improving the terminal heat and drought tolerance in bread wheat. In all the experiments, two wheat cultivars, viz. Mairaj‐2008 (drought and heat tolerant) and Faisalabad‐2008 (drought and heat sensitive), were raised in pots. Both wheat cultivars were raised under ambient conditions in the wire house till leaf boot stage (booting) by maintaining the pots at 75% water‐holding capacity (WHC). Then, managed drought and heat stresses were imposed by maintaining the pots at 35% WHC, or shifting the pots inside the glass canopies (at 75% WHC), at booting, anthesis and the grain filling stages. Drought stress reduced the grain yield of wheat by 39%–49%. Foliar application of AWEs improved the grain yield of wheat by 26%–31%, while seed priming with AWEs improved the grain yield by 18%–26%, respectively, than drought stress. Terminal heat stress reduced the grain yield of wheat by 38%. Seed priming with AWEs improved the grain yield by 21%–27%; while foliar application of AWEs improved the grain yield by 25%–29% than the heat stress treatment. In conclusion, the exogenous application of AWEs improved the stay green, accumulation of proline, soluble phenolics and glycine betaine, which helped to stabilize the biological membranes and improved the tolerance against terminal drought and heat stresses.

Moringa leaf extract improves biochemical attributes, yield and grain quality of rice (Oryza sativa L.) under drought stress

“…The current study revealed that MLE application significantly improved gas exchange attributes, physiological responses, enzymatic activities and productivity of rice crop under drought stress. The findings relating to gas exchange attributes are in agreement with previous studies reporting that drought stress significantly reduced A, gs and E [28,29]. The A and other activities in flag leaf are the major source of crop productivity; however, these are susceptible to abiotic stresses, including drought stress [30].…”

Seed Priming with Sorghum Water Extract Improves the Performance of Camelina (Camelina sativa (L.) Crantz.) under Salt Stress

“…Seed priming with allelopathic water extract significantly improves the seed emergence, plant growth, and yield of various field gown crops, especially under environmental cues [ 33 , 34 , 35 ]. Under heat and drought stress, seed priming with allelopathic water extract improves the stay green, proline, and phenolic content, and stabilizes the biological membrane, thereby enhancing the plants’ tolerance to abiotic stresses [ 33 ]. Under salinity stress, seed priming with 5% aqueous sunflower extract can enhance the tolerance in rice cultivars [ 36 ].…”

“…Various allelochemicals have been identified in several plants, which can improve crop performance under normal and stress conditions. The exogenous application of allelopathic extracts may contribute to the production of endogenous secondary metabolites, which helps crops to perform better even under environmental cues [ 33 ]. The improved crop performance under exogenous application of allelopathic aqueous extract may be due to the increased accumulation of compatible solutes.…”

“…The improved crop performance under exogenous application of allelopathic aqueous extract may be due to the increased accumulation of compatible solutes. In addition, under exogenous application of allelochemicals, the increased tolerance of crops may be due to improved water relations, enhanced photosynthesis, better absorption of water and nutrients, stomatal conductance, and antioxidant defense system [ 33 , 37 , 38 , 39 , 40 , 41 ]. When released from plants, allelochemicals may have to undergo some metabolic or environmental alterations in structure before they can exert biological activity.…”

Water Deficit and Recovery-Induced Changes in Growth, Photosynthetic Characteristics, Antioxidant Enzymes and Yield of Two Tartary Buckwheat Genotypes

“…Adaptive strategies that are induced during the drought process help plants survive (Nguyen et al 2016). Plants such as maize (Zea mays L.) reduce tissue dehydration, either via tolerance to lower tissue water potential or by maintaining the water potential (Wu and Cosgrove 2000;Farooq et al 2017Farooq et al , 2018. To successfully minimize water loss, plants limit transpiration by decreasing leaf area, closing their stomata and accelerating leaf senescence, resulting in improved water-use efficiency (WUE) (Franks et al 2015;Farooq et al 2019) or reduced photosynthesis (Shi et al 2016).…”